Various platinum compounds and complexes have been used heretofore to promote hydrosilation reactions. The platinum compounds and complexes which have been used to promote hydrosilation reactions such as the addition of organosilicon compounds containing .tbd.SiH groups to compounds containing aliphatic unsaturation are compounds such as chloroplatinic acid, platinum chloride-olefin complexes, platinum chloride-cyclopropane and complexes derived from the reaction of alcohols, ethers, aldehydes, ketones and vinyl siloxanes with chloroplatinic acid.
While chloroplatinic acid and elemental platinum may be used as catalysts for hydrosilation reactions, they have certain disadvantages. For example, chloroplatinic acid is insoluble in many organic solvents and is not always effective at low concentrations. Moreover, these catalysts are subject to poisoning in the presence of a number of common materials. The disadvantages of elemental platinum and chloroplatinic acid with respect to poisoning and speed of reaction have been overcome by the use of the platinum compounds described above, such as the platinum-olefin complexes described in U.S. Pat. Nos. 3,159,601 and 3,159,662 to Ashby. Faster and more active catalysts are described in U.S. Pat. Nos. 3,715,334; 3,775,452; and 3,814,730 to Karstedt, in which platinum vinyl siloxane complexes are treated with a base material to form a catalyst in which the halogen to platinum ratio is about 1:1 or less than 1:1.
It has been found that a platinum-styrene complex which is formed in the presence of a basic material and has a halogen to platinum ratio of more than one, but less than four gram atoms of halogen per gram atom of platinum, is substantially more stable than other platinum complexes and maintains its level of activity for longer periods of time.
Therefore, it is an object of this invention to provide a novel platinum catalyst. Another object of this invention is to provide a platinum catalyst for effecting the addition of SiH-containing organosilicon compounds to unsaturated organic compounds. Still another object of this invention is to provide a catalyst which is highly reactive at room temperature and is more effective at lower concentrations. A further object of this invention is to provide a catalyst which is more stable and maintains its level of activity for longer periods of time.